proximity_constraint.h

/*
 * Copyright (c) 2020, The Regents of the University of California (Regents).
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 *
 *    2. Redistributions in binary form must reproduce the above
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 *    3. Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * Please contact the author(s) of this library if you have any questions.
 * Authors: David Fridovich-Keil   ( dfk@eecs.berkeley.edu )
 */

///////////////////////////////////////////////////////////////////////////////
//
// (Time-invariant) proximity (inequality) constraint between two vehicles, i.e.
//           g(x) = (+/-) (||(px1, py1) - (px2, py2)|| - d) <= 0
//
// NOTE: The `keep_within` argument specifies the sign of g (true corresponds to
// positive).
//
///////////////////////////////////////////////////////////////////////////////

#ifndef ILQGAMES_CONSTRAINT_PROXIMITY_CONSTRAINT_H
#define ILQGAMES_CONSTRAINT_PROXIMITY_CONSTRAINT_H

#include <ilqgames/constraint/time_invariant_constraint.h>
#include <ilqgames/utils/types.h>

#include <glog/logging.h>
#include <memory>
#include <string>

namespace ilqgames {

class ProximityConstraint : public TimeInvariantConstraint {
 public:
  ~ProximityConstraint() {}
  ProximityConstraint(const std::pair<Dimension, Dimension>& dims1,
                      const std::pair<Dimension, Dimension>& dims2,
                      float threshold, bool keep_within,
                      const std::string& name = "")
      : TimeInvariantConstraint(false, name),
        xidx1_(dims1.first),
        yidx1_(dims1.second),
        xidx2_(dims2.first),
        yidx2_(dims2.second),
        threshold_(threshold),
        keep_within_(keep_within) {
    CHECK_GT(threshold_, 0.0);
  }

  // Evaluate this constraint value, i.e., g(x).
  float Evaluate(const VectorXf& input) const;

  // Quadraticize the constraint value and its square, each scaled by lambda or
  // mu, respectively (terms in the augmented Lagrangian).
  void Quadraticize(Time t, const VectorXf& input, MatrixXf* hess,
                    VectorXf* grad) const;

 private:
  // Position dimension indices for both players.
  const Dimension xidx1_;
  const Dimension yidx1_;
  const Dimension xidx2_;
  const Dimension yidx2_;

  // Nominal distance threshold.
  const float threshold_;

  // Keep within (or without), i.e., orientation of the inequality.
  const bool keep_within_;
};  // namespace ProximityConstraint

}  // namespace ilqgames

#endif